Ozone & Meteorology Monitoring

Air quality monitoring station at Great Smoky Mountains National Park, North Carolina and Tennessee.

The NPS Air Resources Division operates a network of air quality monitoring stations that measures meteorological parameters and ozone. This is sometimes referred to as the Gaseous Pollutant Monitoring Program (GPMP). Many stations are jointly operated with the Environmental Protection Agency (EPA) through Clean Air Status and Trends Network (CASTNet).

The GPMP historically concentrated on determining the levels of two gaseous air pollutants, ozone and sulfur dioxide, which can be toxic to native plants. Other gaseous pollutants (e.g., other photochemical oxidants, nitrogen compounds, and toxic organic compounds) are also of interest to the NPS because they relate to physiological, morphological, or historical injury to park biological resources, or to global climate change.

Locations

Data Access

Results

Objectives & Procedures

Resources

Contacts

Ozone Monitoring Locations

Most NPS ozone monitoring locations are operated by the NPS in parks identified as mandatory Class I areas. Class 1 areas, defined by the Clean Air Act, are held to a higher air quality standard than other areas. Some ozone monitoring stations in the parks are operated by State agencies.

Current year exceedance summary tables. These list high ozone concentrations and exceedances of the National Ambient Air Quality Standard (NAAQS) in parks based on screened preliminary data. Preliminary data are used to get a quick look at the high 8-hour ozone averages that exceed 75 ppb.

Monitoring Objectives & Procedures

Objectives

Provide data to help scientists’ asses the risks that certain pollutants pose to natural resources in the parks.

Collect air quality data in parks that reveals how well parks are doing with respect to the national ambient air quality standards set by the EPA. These data are also useful for EPA’s New Source Review permitting program and Prevention of Significant Deterioration program which seek to ensure that new and modified industrial development do not significantly degrade air quality.

Identify air quality trends from measured data to aid in compliance predictions, policy objectives, and regional air quality assessments in areas that lack direct monitoring.

Assist modeling efforts, regional pollution and transportation studies, State Implementation Plan development (to address regional haze), and national air quality control strategies through special studies.

Provide timely NPS air quality information to the public and researchers.

Procedures

The standard NPS monitoring station measures ozone using a UV-absorption analyzer, a transfer standard, a weather station
including wind speed, wind direction, temperature at two heights, solar radiation, relative humidity, and a wetness sensor. Additionally a stacked filter-pack measures sulfate, sulfur dioxide, nitrate, ammonium, and nitric acid, and at some sites a sulfur dioxide. Park staff operate the stations and a contractor maintains and calibrates the network equipment. Data are transmitted nightly, validated, and archived. Hourly data files are transferred to the EPA Air Quality Systems database and are available on the web.

The US EPA has set an ozone national standard (NAAQS) of 75 ppb over an 8-hour period for human health and for natural resources. The standard is a calculated value over 3 years using the 4th highest annual ozone of the daily maximum 8-hour averages. See EPA for the full details.

AirNow – Map of Today’s Ozone. Daily contour plots of ozone concentrations are available from AirNow.gov during the ozone season and include input from National Park Service monitoring stations. These maps are handy for understanding regional distributions and movements of ozone.